The present invention relates to a steering column apparatus which mitigates an impact occurring due to occupant's movement toward a vehicle front side upon an occurrence of a secondary collision.
A steering column provided in a steering column apparatus for steering a vehicle is connected to a vehicle body with sufficient supporting rigidity secured. The steering column is required, upon the occurrence of the secondary collision, to smoothly move toward the vehicle front side along an axis of the steering column and mitigate the impact that acts on the occupant.
As a related art steering column apparatus, for example, it is disclosed in Japanese Patent Provisional Publication “tokuhyou” No. 2007-504986 (hereinafter is referred to as “JP2007-504986”). As disclosed in FIG. 1 in JP2007-504986, a bracket 2 having, in a middle thereof, a slot 6 is mounted on a vehicle body, and a bracket slide 13 shown in FIG. 3 in JP2007-504986 is arranged below the bracket 2. The bracket slide 13 is connected to a sliding block 15 that is arranged in the slot 6 at an upper portion of the bracket 2 via two screws 16 inserted in the slot 6. Further, the bracket slide 13 is connected to a lower surface, at a vehicle rear side, of the bracket 2 via three fastening elements 14. A casing tube 8 provided therein with a steering shaft 9 is joined to the bracket slide 13 by a clamping apparatus 12 via lamella assemblies 11 arranged at both sides of the casing tube 8.
As shown in FIG. 2 in JP2007-504986, when a force A in an axial direction (a shaft direction) of the steering shaft 9 acts on the steering shaft 9, the force A is transmitted to the bracket slide 13. Then when the fastening elements 14 are released, the bracket slide 13 moves toward the vehicle front side with respect to the bracket 2. That is, as shown in FIG. 5 in JP2007-504986, the fastening element 14 is fixed to the bracket 2 via a rivet 21, and a tear-off pin 22 that is formed of plastic is provided between the fastening element 14 and the bracket slide 13. When a force that exceeds a predefined magnitude is applied to the bracket slide 13, the tear-off pin 22 tears, and the bracket slide 13 is released from the fastening elements 14. In other words, a supporting rigidity of the bracket slide 13 is secured by the fastening elements 14. Then, upon the occurrence of the secondary collision, the tear-off pin 22 tears and the bracket slide 13 is released, the bracket slide 13 thus moves toward the vehicle front side along the slot 6. Here, FIG. 7 in JP2007-504986 shows other embodiment.